Research Journal of Pharmaceutical, Biological and Chemical Sciences

Research Journal of Pharmaceutical, Biological and Chemical Sciences A Highly Selective Visible Spectrophotometric Estimation of Pd (II) Using Ambroxol Hydrochloride. B Saritha and T Sreenivasulu Reddy*. Department of Chemistry, S.K.University, Anantapur-515003, Andhra Pradesh, India. ABSTRACT The present paper reports a simple, accurate, precise, sensitive, and highly selective visible, spectrophotometric method for the estimation of Pd(II) using ambroxol hydrochloride. The method is based on the colour reaction between ambroxol and palladium (II) in the ph range 3.0 8.0 forming a yellow coloured complex solution. The coloured species has maximum at 410 nm. Studies were carried at the maximum absorption at ph 6.0. A 0.1% sodiumdodesylsulphate (SDS) keeps the complex in solution. The colour intensity attains a maximum value after 30 minutes of mixing the various components. Under the optimum conditions Beer s law is obeyed in the range 1.5-18.5 µg/ml. The straight line plot obeyed the equation A = 0.0572 C + 0.0007. The molar absorptivity and Sandell s sensitivity are 6.10 10 3 lmol -1 cm -1 and 0.0175 µg cm -2 respectively. The standard deviation of the method for ten determinations of 5.0µg/ml ambroxol is 0.0021. The correlation coefficient (r) of the experimental data of the calibration plot is 0.9999. The effect of various foreign ions was studied. The composition of the complex is established as 2:1[(Pd(II) : Ambroxol]. The stability constant of the complex is 2.090 10 11. The proposed method is successfully applied for the determination of Pd(II) in alloy steels and natural water samples. Keywords: Pd(II), Ambroxol hydrochloride, Visible spectophotometric selective method *Corresponding author March - April 2014 RJPBCS 5(2) Page No. 1611

INTRODUCTION Palladium is a platinum group metal discovered by W.H. Wollaston in 1803.It is rare and lustrous silvery metal. Palladium and its alloys have wide range of applications both in chemical industry and instrument making[1]. Palladium forms a good catalyst and is used to speed up hydrogenation and dehydrogenation reactions, as well as in petroleum cracking. Palladium is employed in many electronic devices including computers, cellphones, multilayer capacitors and low voltage electrical contacts as well as in dentistry and medicine [2]. Palladium is used in jewellery, watch making and blood sugar strips. Palladium is one of the three most popular methods used to make white gold alloys [3]. Due to its wide applications there is a need for the development of a sensitive, highly selective and precise method for its determination at micro levels. Several analytical techniques such as atomic absorption spectrometry [4], neutron activation analysis [5] and pre-concentration and separation methods such as flow injection method, hollow fiber micro extraction, solid phase micro extraction and spectrophotometry [6-33]. Among them spectrophotometric methods are preferred because of there low cost and simplicity of operation. However, the survey of literature revealed that there is no report of a sensitive and specific spectrophotometric method for determination palladium (II). In this communication we report a specific, sensitive and precise visible spectrophotometric method for the determination of palladium (II) using ambroxol hydrochloride. MATERIALS AND METHODS All chemicals and solvents used were of analytical reagent grade. Solutions Palladium (II) solution 1 g of palladium chloride (Loba Chime Ltd.) is dissolved in distilled water in a 100ml standard flask and standardized [34]. Working solution is prepared by suitably diluting the stock solution. Ambroxol solution Ambroxol is 4-[[2-amino-3,5-dibromophenyl ) methyl]amino] cyclohexanol (or) N (trans P hydroxy cyclohexyl ) (2 amino -3,5 dibromobenzyl ) amine. It is a white crystalline powder freely soluble in water and its molecular formula is C 13 H 18 Br 2 N 2 O (M. W. = 378.11). Its molecular structure is Br Br NH 2 NH OH March - April 2014 RJPBCS 5(2) Page No. 1612

100 mg of ambroxol hydrochloride was weighed accurately and transferred into a 100 ml standard flask, dissolved and made up to the mark in double distilled water. This solution was diluted as required. Buffer solutions were prepared by adopting the standard procedures reported in the literature [20]. The solutions employed for the preparation are given below. ph Constituents 0.5 3.0 1 M Sodium acetate + 1 M Hydrochloric acid 3.0 6.0 0.2 M Sodium acetate + 0.2 M Acetic acid 7.0 1.0 M Sodium acetate + 0.2 M Acetic acid 8.0 12.0 2.0 M Ammonia + 2.0 M ammonium chloride Instruments A Shimadzo UV-Visible recording spectrophotometer (UV-160A) measuring wavelength at 200-1100 nm,and wave length accuracy + 0.5nm with automatic wavelength correction. An ELICO digital ph meter was used for measuring the ph of buffer solutions. The reproducibility of measurements is within 0.01 ph. Procedures Preparation of alloy steel samples A 0.1-0.5g of steel sample was dissolved in a minimum volume of aquaregia by slow heating an sand bath and then heated to fumes of oxides nitrogen. After cooling,5-10 ml of 1:1 H 2 SO 4 were added and evaporated to dryness. Sulphuric acid treatment was repeated three times to remove all the nitric acid. The residue was dissolved in 20 ml of distilled water and filtered. The filtrate was made up to the mark in a 100 ml volumetric flask with distilled water. The solution was diluted to obtain the concentration in the required range. Absorbance spectrum 5ml of buffer solution of ph 6.0, 1ml of Pd(II) [2 10-3 M] solution and 1 ml of ambroxol [1 10-2 M] were taken in a 10 ml volumetric flask and made up to the mark with distilled water. The absorbance of the solution was measured in the wavelength region 300-600 nm against a blank consisting of 5 ml of buffer solution made up to the mark with distilled water in a 10 ml volumetric flask. Determination of Palladium(II) 5ml of buffer solution of ph 6.0, 1ml of ambroxol [1 10-2 M] solution and varying volumes of Pd(II) [2 10-3 M] solution were taken in a series of 10 ml volumetric flasks and March - April 2014 RJPBCS 5(2) Page No. 1613

the contents of each flask were made up to the mark with distilled water. The absorbance of the solution was measured at 410 nm using buffer blank. Effect of SDS Concentrations In order to improve the sensitivity the method and to avoid precipitation of the complex species,the effect of various surfactants on the ambroxol Pd(II) complex solution was studied.of all the surfactants studied sodiumdodesylsulphate(sds) is found to enhance the absorbance. The effect of varying concentration of SDS on the absorbance studies are reported in Table-1. The study reveals that 0.1% of SDS gives maximum absorbance for the system. Interference studies In order to asses the applicability of the method, the effect of presence of various foreign ions that are generally associated with Pd(II) in real samples is assessed by adding varying amounts of foreign ions to a fixed amount of Pd(II) (5.0µg/ml) solution and the absorbance measurements are carried out under optimal conditions.the concentration (µg/ml) at which various ions can cause an error + 3% in absorbance is taken as its tolerance limit. The results are given in Table-2 RESULTS AND DISCUSSION Pd(II) reacts with Ambroxol hydrochloride in the ph range 3.0-8.0 forming an yellow coloured complex in solution. The absorption spectrum of the yellow coloured Pd(II) Ambroxol complex shows(fig-1) absorption maximum at 410 nm. At this wave length either Pd(II) or ambroxol has no significant absorbance. The colour intensity of the complex is maximum in ph range 5.5-6.5. Hence studies were carried at ph 6.0. The colour formation attains maximum intensity after 30 minutes of mixing the various components. There after the colour of the complex remains stable for more than 24 hours. A five fold molar excess of ambroxol hydrochloride is sufficient to produce maximum absorbance. To increase the sensitivity a one percent SDS solution is added. The absorbance varied linearly with the concentration of Pd(II). Beer s law is obeyed in the range 1.5-18.5 µg/ml of Pd(II). The straight line plot obeyed the equation A = 0.0572 C + 0.0007. The molar absorptivity and Sandell s sensitivity are 6.100 10 3 lmol -1 cm -1 and 0.0175 µg cm -2 respectively. The standard deviation of the method for ten determinations of 5.0 µg/ml Pd(II) is 0.0021. The correlation coefficient (r) of the experimental data of the calibration plot is 0.9999. The effective range of concentration for accurate determination of Pd(II) as ascertained from Ringbom s plot is 2.0-18.0 µg/ml. The limit of detection is 0.1213 µg/ml. The composition of the complex was studied by Job s method and molar ratio method. Both the methods confirm that the ratio of [Pd(II) : Ambroxol ]as 2:1. The stability constant of the complex as evaluated from the Jobs method is 2.090 10 11. The effect of associated metal ions studied and the results are shown in table -2. The data reveal that the method is specific at ph 6.0 as none of the association metal ions show any interference. March - April 2014 RJPBCS 5(2) Page No. 1614

Wavelength (nm) Fig.:1. Absorption spectra of a) Pd(II) vs. buffer blank; b) ABX vs. buffer blank; c) ABX Pd(II) vs. buffer blank [Pd(II)] = 5.0 x 10-4 M ; [ABX]= 2.0 X 10-5 M Table 1: Effect of SDS Concentration on the absorbance S. No Volume of 1% SDS solution Absorbance 1 0.20 0.316 2 0.50 0.438 3 1.00 0.450 4 1.50 0.451 5 2.0 0.449 [ABX] = 1 x 10-3 M = 410 nm [Pd(II)] = 1.25 x 10 4 M ph = 6.0 Applications The method developed was successfully applied for the determination of Pd(II) in alloy steel samples and water samples. The alloy solution prepared as described above was analysed by the present method and results are reported in table-4. Water samples were spiked with known amounts of Pd(II) and were analysed by the proposed method and samples were simultaneously analysed by atomic absorption spectophotometry and the results are compared[table-5]. March - April 2014 RJPBCS 5(2) Page No. 1615

Table 2: Tolerance limits of foreign ions Ion Tolerance Tolerance Ion limit(µg/ml) limit(µg/ml) Iodide 10 Mo(VI) 349 Bromide 530 Ir(III) 629 Chloride 610 Co(II) 123 Fluoride 420 Ba(II) 236 Carbonate 725 Zn(II) 313 Sulphate 1520 Ce(IV) 218 Nitrate 948 W(VI) 397 Phosphate 1630 Mn(II) 108 Oxalate 1190 V(V) 103 Thiocyanate 356 Ag(I) 281 EDTA 1091 U(VI) 428 Tartrate 1462 Zr(VI) 149 Citrate 687 Se(IV) 215 Acetate 878 Th(IV) 350 Ascarbate 1191 Te(IV) 430 Na(I) 355 Pb(II) 267 K(I) 936 Ga(III) 138 Mg(II) 548 In(III) 252 Ca(II) 926 Y(III) 289 Ru(III) 357 La(III) 685 Cr(VI) 159 Ti(IV) 212 Fe(III) 328 Ni(II) 253 Cu(II) 257 Al(III) 102 Cd(II) 457 Au (III) 120 Hg(II) 367 NH 4 (I) 268 Pt(II) 96 [palladium (II)] = 5 g/ml ph = 6.0 Table 3: Optical and regression characteristics, precession and accuracy of the Proposed method for Pd(II) Parameter Pd(II) Analytical Wavelength (nm) 410 Beer s law limits (µg/ml) 1.5 18.5 Limits of detection (µg/ml) 0.1213 Limits of quantization (µg/ml) 0.3640 Molar absorptivity (l.mo1-1 cm -1 ) 6100 Sandell s Sensitivity (µg/cm 2 ) 0.0175 Regression equation ( y = a + b x ) Slope (b) 0.0571 Intercept (a) 0.0007 Correlation coefficient ( ) 0.9999 Standard deviation(sd)(5.0 µg/ml) 0.0021 March - April 2014 RJPBCS 5(2) Page No. 1616

Table 4: Analysis of alloys Alloy Composition Palladium found * (µg) Error (%) (Pd-Au alloy) Pd, 50: Au, 50 50.28 +0.56 Pd-Cu alloy Pd,60; Cu:40 59.5-0.86 Pd- Ag alloy Pd,60; Ag,40 60.40 0.60 * Average of seven determinations Table 5: Determination of Pd(II) in water samples Sample No Amount of Pd(II) added(µg) Pd(II) found present method* (µg) Pd(II) found AAS method (µg) 1 6.0 5.89 6.91 2 8.0 7.88 7.93 3 10.0 9.96 9.99 * Average of seven determinations CONCLUSIONS As reported already literature survey do not reveal the report of any specific spectrophotometric method for the determination of Pd(II).The present method for the determination of Pd(II) is a simple, selective and sensitive. The present visible spectrophotometric procedure which is not only fairly rapid, precise and highly sensitive but also is within the reach of an ordinary chemical laboratory. The linearity parameter and the corresponding regression data indicates excellent linear relationship (r =0.9999). Other spectrophotometric methods reported for its determination either use of costly instrumentation or suffer from interference of associated ions. The method is easily applied for the determination of Pd(II) in alloy steels and natural waters. ACKNOWLEDGEMENTS The authors thank the department of Chemistry of S.K.University Anantapur,for providing the necessary facilities. One of authors (B.Saritha) thanks UGC for providing financial assistence under BSRB scheme. REFERENCES [1] Zhang L., Ma, D., Li, J., and Wang, Y., Anal. Sci., 2006. 222 (7), 989-992. [2] Yang, b., Zhu, L., Huang, Z., Yang, G., and Yin, J., Guijinshu, 2005, 26(1), 39-42. [3] Absalan G, Safari A and Massoumi A, Microchemical J, 1988,(37) 212. [4] Lahiri S,Dey S, Badiya T K, Nandy M, Balu D and Das NR, Appl. Radio Isotopes, 1997 (48) 549. [5] Eskandari H & Karkaragh G I, Bull Korean Chem Soc, 2003 (24) 1731. [6] Sayed Juned A and Bhole Arjun B Annals of Biological Research, 2011,2(1): 9-16 [7] Parameshwara P,Karthikayan J,Nityananda Shetty A & Prakash Shetty, Ann Chim, 2007 (97) 1097. [8] Hall I H, Lackey C B, Kistler T D, Durham R W Joud E M, pharmazie, 2000 (55) 937. [9] Reddy B k, Reddy K J, Kumar J R, Kumar A k & Reddy Av Anal Sci, 2004 (20) 925. March - April 2014 RJPBCS 5(2) Page No. 1617

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